Steve Gleason was a star player for the New Orleans Saints before being diagnosed with a rapidly progressive form of ALS, commonly known as Lou Gehrig’s disease, at age 34. With their first child on the way, Gleason and his wife Michel confront their ever-changing new reality with unflinching honesty in front of the camera. GLEASON, a remarkable portrait of a man and his family dealing with a devastating disease, is by turns revealing, heartbreaking, humorous and undeniably human. AFI spoke to director Clay Tweel ahead of the film’s AFI DOCS premiere. What led you to documentary filmmaking? What really led…